Methods and devices for pre-loading bearings



E. SCHAFRANIK Nov. 18, 1958 METHODS AND DEVICES FOR PRE-LOADING BEARINGSFiled Sept. 22, 1954 my mm@ )N` w I ,.W.m. UW uw m/ uv EE ma En p nim zEn na Es En .a Em i. ns E Mm NN .w wn

N .M .WNN .Q N www .x NN wf N a w @DE ,f 1.. m. Q uw -m.\ Q. hw QWN QNUnited States paf O METHODS AND DEVICES FOR PRE-LOADING BEARINGS ErichSchafranik', Providence, R. I., assignor to Abrasive Machine ToolCompany, East Providence', R. I., a corporation of Rhode IslandApplication September 22,1954, Serial No. 457,755

5 Claims. (Cl. 308-6) This invention relates to improvements in methodsand Ldevices for pre-loading bearings. More'particularly the inventionprovidesA an improved method and means forv pre-loading bearings of thegeneral types employedA befv tween relatively slidableV elements andparts ofV machines whose movable elements or parts may be mounted forsions and relationships of machined surfaces and partsv which aremounted for relative movements, and various` pre-loading procedures anddevices are well known. The` present invention improves upon the priorproposals by makingit possible and commercially feasible to'pre-lo'adbearingsmore effectively and more `economically as com' pared with anyof the prior comparable'proceduresand devices of which'I am aware.

Heretofore, it has been conventional practice; in the case of bearingsfor relatively slidable 'machine elements, to pre-load the bearings bymeans of gib strips'through which varying degrees of pressure ymay beapplied toY relatively slidable elements by tightening set-screws orthelike which may be suitably distributed at intervals along a gibstrip. The gib strip methodlof pre-loading bearings has proven fairlysatisfactory but, when the gibV strips arel of a preferred taperingvariety, there are -deff inite limitations upon the length ofbearingswhich canbe pre-loaded in accordance with prior gib strip procedur-es.Also, particular ones ofthe distributed set screws may be-tightened moreor less than others which results in an unequal distribution of.thepre-loading pressures,

l Pre-loading of prior circular bearings, such as ball bearings,customarily has been :accomplished by forcingV one. ballrace toward thecoacting ball raceby meanseof set screws, or the like,and here againunequal distribu-i tion of. the pre-loading' pressures frequentlyoccurs.

It is among the objects of thevinvention-toprovide aV bearingpre-loading method and means whereby straight, or. curving,` orcircular, 4bearings may be more eiectively and more uniformly preloadedtosuit particularrequirements, as: compared withpriorbearing'pre-loading pro-V The invention provides for applying predetermined substantially uniformly' distributedv pre-loading cedures,

pressure to a bearing member, such` as a 'ballrace, for

example, by means of `av multiplicity of thrustelernentsconfined in aspace adjacent to the -said Vbearing -mem` ber andextendingsubstantially throughout the extent-of said bearing member, all orgroupsof said thrust` ele# ments' being crowded together in saidl confiningspace withfsome of said thrust elements in contact with saidj bearingmember and supporting others out-ofy Contact therewith, wherebypre-loading pressure applied to one i ly to; said bearing member atdistributed locations-of con-V Y 12,860,930 IitenteclV Nov. 18, 1958 ICC2 Y tact of particular vones of said thrust elements with said bearingmember. e Y

Anotherobject of vthe invention is toprovide a bearjV ing pre-loadingmethod and means' whereby a bearing member which constitutes a ballbearing race, or the like, is backed by a` multiplicity of thrustelements crowded together in a coniining space with alternate ones ofsaidv elements in contact with said bearingmember and alternate onessupported by adjacent elementsout of Contact therewith, whereby amanualmeans for applying pressure to one of the said supported outof-co'nta'ctelements" effects predetermined rsubstantially uniform pre-'loadingofthe bearing' lwiththev pre-loading pressure transmitted to' all' ofvthe e irl-contact thrust elements through y the supported'out-offcon'tact elements. y Yetanther'object ofthe invention is toprovide al.. bearing p`rt':lcl a"din`gl device wherein a multiplicityyof cylindrical rollers are' confined within 3a space behind a bearingmember with alternate rollers in contactl with the bearing member yandalternate rollers supported byk adjacentl rollers out-ofcontact withthe'y bearing member,- and wherein substantially uniform distributedpre-loadingof the bearing maybe accomplished by subjecting one or aplurality of the out-ofcntact rollers to a predete'r'mned amount ofpre'ssure which becomes distributive-v l'y transrriittc'sdI to thebearing member at the locations of the incontact rollers; l 1

It" is', moreover, my purpose adobje'c't generallyv to improveV-bearing" pre-loading' procedures and Ydevices and mUreesp'eCiaIIy t6provide for more efectively and more e uniformly transmittingpre-,loading pressures to `a bearingf' member," as co'iipa'r'ed withprior pre-loading proced'ures. n

In"the"'acc'on1p aying" drawing: t Fig'Ql is afcros'ssectional View oftwo relatiifelyr slida ble members of amachihe' at location of onefoVtwo similar linear ball bearings which extend in parallelism in"a commonnhorizorit'al plane' at spaced locations, the section4 being'on line 1'-1"of Fig. 3;'k Y d ,u Fig. Y2'- is'V a cross-sectional view on' lineofFvig. v1;

Fig. 3 is a cross-sectional viewonline 3;-3 of Eig. 1 v

but turnedclockwisethrouglli'QO; and' I Fig. 44 is'aview similar toFig",` 1 but showing/"a modilied form of the invention?Y n,

*Referring-"to thedrawing", the invention is illustrated in itsembodimentv in a' machine having two'l machine parts* 10, 124 which arerelatively slidable, one upon!4 other, withanti-friction'bering meansbetween them. For example, the part V10- may be' a machine tool mem# beronf which the part 12 is slidabl'e as aA table member or 4crossslidememberf v Asherein represented', opposite sides of they nierrlber` 1-0are grooved'at 14', oily one side" being shown""i"r"tli1ef3drawing,`and\ a race strip 16x is se'at'ed in each groove 14 and'secured' against movement therein by any suitable means (not shown).-AnY under "portion "-olmemberT 12` is* 'grooved' at' v1 '8 'ati oppositesides of the`member`,' only one`s`ide'V being" slic'rvvli; and-iaracestrip 20-*is mounted in` e'ach groove 18" a'rd' retained againstlongitudinal moveientf therein' by' any' suitable means (not shown).lHowever, the race st'ips 20 are mountedin `.the grooves' 18` forpermissible"r=` stricted vmovement indirections generally towardandffrornthe adjacentrace strips 16. i 2 y As best seen inFig.. 3, a racestrip 16 is generallyoppo'- n site a race strip`20, and the opposedfaces ofthe adjacent raceY strips are longitudinally groovedv at 17and-,21 readjacent'sitr'ips' 16, 20 ih suitably"spaced relationsoftliatW Y the'm'ember'lZfis supportedE onfl the distribute'il"I ballsZiff:

at opposite sides of the member 10. Preferably, a ball retainer 24 has aseries of suitably spaced holes 26 therein within each of which one ofthe bearing balls 22 loosely engages, the Vretainer being free toV movelongitudinally between the race strips 16, to maintain a predeterminedspacing of the` bearing balls as the balls rollin -one direction or theother along the race strips 16 in response to a sliding movement ofmember 12 relative to member 10. According to the invention, each racestrip 20 provides a Wall 20 behind which the member 12 is'longitudinallygrooved at 28 to provide a confining space within which a multiplicityof thrust elements 30 are confined in crowded-together relation. Asrepresented, the thrust elements 30 are short cylindrical rollers whosecrowding within groove space 28 is such that alternate ones of thethrust elements are in engagement with the wall 20' and other alternateones are in contact with the bottom wall of the groove 28 in member 12,with each pair of adjacent rollers which are in contact with lthe sameone of said walls supporting and maintaining an intermediate roller incontact with the other of said walls. Hence, if any one of said thrustelements is forced in direction toward the wall with which it is out ofcontact, all of the thrust elements become more tightly crowded togetherin said groove space 28. and increased distributed pressure becomesapplied to movable wall 20 tending to move it toward the adjacent racestrip 16 with resulting application of pre-loading pressure to thebearing balls 22 relatively uniforrnly at each of the distributedlocations of the thrust elements which are in contact with wall 20'. lnthe drawing. a set screw 32 is adiustable in member 12 at the locationof the thrust element 30' by means of which the thrust element 30' maybe forced further between the two thrust elements in contact with theelement 30' to accomplish a said relatively uniformly distributedpre-loading of the bearing between members 10, 12. While a single set`screw 32 will suice in many cases, it may be found desirable to providean additional set screw or set screws 32' when any particular bearing orbearings have substantial length.

lt will be obvious that the thrust elements 30, 30' need not becylinders but might be balls or elements having hexagonal cross-section;it being essential only that the thrust elements be capable of beingcrowded together, more or less, Within a coniining space in response topressure applied to any one or any spaced plurality of the thrustelements.

Also, it should be understood that the invention is in no sense limitedto bearings for members having relative movement in a straight line orin a single plane. Obviously, the grooves 14. 18 in members 10, 12 mayhave extent on any desired curvatures and the race strips 16. 20 may becorrespondinglv curved to provide for sliding movements of member 12 ina curved path.

. Furthermore. the disclosure is applicable to circular hearings. Forexample, in Fig. 3, the grooves 14, 18 in members 10. 12 may extendcircularlv around 'the respective members 10, 12 in a horizontal planewith the member 12 annularly supported on a circular ball bearlng forrotation about the axis of the circular bearing, in which case thepre-loading of the circular bearing would be accomplished in the samemanner as described in connection with Figs. 1 3.

Fig. 4 illustrates a modification in which spaced groups of the thrustelements 30 are separated by spacing struts 34 which transmit pressureapplied to any one or more of the thrust elements to the separatedgroups of thrust elements. The pre-loading action in Fig. 4 issubstantially the same as described in connection with the Figs. l-3embodiment. Y

Various changes may be made in the details of the disclosed -inventionwithout departing from the spirit and scope of the invention as definedin the appended claims, and it is intended that the patent shall coverby suitable expression in the appended claims whatever features ofpatentable novelty exist in the invention disclosed.

I claim as my invention:

l. In a bearing having anti-friction bearing elements between anddistributed along a substantial portion ofthe extent of two members ofwhich one is adapted to be driven relative to the other, meansconstituting a race strip engaging all of said anti-friction bearingelements and mounted for limited movements relative to said members indirections toward and from said anti-friction bearing elements, meansdefining a space between said race strip and one of said members, amultiplicity of thrust elements confined and crowded together withinsaid space with alternate ones of the thrust elements engaging said racestrip and supporting intervening thrust elements in engagement with saidone of said members, and manually operable means for applying pressureto only one of a multiplicity of said intervening thrust elementsthereby to apply distributed substantially equalized pressure to saidrace strip throughout a substantial portion of the extent of the saidrace strip where said multiplicity of intervening thrust elements aresupported by said wall-engaging thrust elements.

2. In a bearing having anti-friction bearing elements between anddistributed along a substantial portion of the extent of two members ofwhich one is adapted to be driven relative to the other, meansconstituting a race strip engaging all of said anti-friction bearingelements and mounted for limited movements relative to said members indirections toward and from said anti-friction bearing elements, meansdefining a space between said race strip and one of said members, saidspace extending substantially throughout the extent of said race strip,a multiplicity of thrust elements confined in crowdedtogether relationwithin said space with successive ones of the thrust elementsalternately engaging said race strip and said one of said memberswhereby adjacent thrust elements which are in engagement with said racestrip maintain an intervening thrust element in engagement with said oneof said members and adjacent thrust elements .which are in engagementwith said one of said members maintain an intervening thrust element inengagement with said race strip, and manually adjustable means at onlyone of said thrust elements for varying the pressure exerted by eachthrust element on each other thrust element thereby to vary thedistributed pressure exerted on said race strip by the thrust elementswhich are in engagement therewith.

3. In a bearing having anti-friction bearing elements between anddistributed along a substantial portion of the extent of two members ofwhich one is adapted to be driven relative to the other, meansconstituting a race strip engaging all of said anti-friction bearingelements and mounted for limited movements relative to said members indirections toward and from said anti-friction bearing elements, meansdefining a space between said race strip and one of said members, saidspace extending substantially throughout the extent of said race strip,a

multiplicity of thrust rollers confined in crowded-together' parallelismwithin said space with successive thrust rollers alternatelyv engagingsaid race strip and said one of said members whereby the thrust rollerswhich engage said race strip maintain intervening thrust rollers inengagement with said one of said members and the thrust rollers whichengage said one of said members maintain intervening thrust rollers inengagement with said race strip, and manually operable means forapplying force directly to only one of said thrust rollers thereby toforce it between twoothers for increasing the distributed pressureexerted on said race strip by all of the thrust rollers in engagementtherewith.

4. In a machine having two members of which one is Y mounted for slidingmovements on the other and having anti-friction bearing elements engagedbetween said members, means for effecting `predetermined pre-loading ofthe bearing provided by said bearing elements, comprising a race stripbetween said members in engagement with all of said bearing elements andmounted for limited movements relative to said members in directionstoward and from said bearing elements, means dening a space between saidrace strip and one of said members, said space extending throughout asubstantial portion of the extent of said one of the members, thrustelements conined and crowded together Within Said space with alternatethrust elements engaging said race strip and said one of the memberswhereby the thrust elements mutually support and maintain each other inengagement respectively with said race strip and said one of saidmembers, and manually adjustable means for applying pressure to only oneof said thrust elements thereby to increase the distributed pressureexerted on said race strip by all of said thrust elements in engagementtherewith.

5. The method `of pre-loading a bearing having antirfric/tion elementsbetween two relatively movable members, comprising arranging a racestrip in contact with all of the anti-friction elements, 'providing amultiplicity of thrust elements in contined crowded-together relationbetween the race strip and one of said members with alternate thrustelements in contact with said race strip and supporting interveningthrust elements in contact with said one of the members, and applyingpressure to only one of said intervening thrust elements to eiectsubstantially uniformly distributed pre-loading of the bearing with thesaid applied pressure distributively transmitted to -said race strip atthe locations of Contact of said alternate thrust elements therewith.

References Cited in the tile of this patent UNITED STATES PATENTS1,320,836 Brinkman Nov. 4, 1919 1,443,789 Humphreys Jan. 30, 19232,244,434 Shaw June 3, 1941 2,526,518 Turrettini Oct. 17, 1950 FOREIGNPATENTS 245,763 Switzerland Aug. 16, 1947

